The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_sysctl.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed to Berkeley by
    6  * Mike Karels at Berkeley Software Design, Inc.
    7  *
    8  * Quite extensively rewritten by Poul-Henning Kamp of the FreeBSD
    9  * project, to make these variables more userfriendly.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 4. Neither the name of the University nor the names of its contributors
   20  *    may be used to endorse or promote products derived from this software
   21  *    without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   33  * SUCH DAMAGE.
   34  *
   35  *      @(#)kern_sysctl.c       8.4 (Berkeley) 4/14/94
   36  */
   37 
   38 #include <sys/cdefs.h>
   39 __FBSDID("$FreeBSD: releng/7.3/sys/kern/kern_sysctl.c 192538 2009-05-21 14:51:31Z jhb $");
   40 
   41 #include "opt_compat.h"
   42 #include "opt_ktrace.h"
   43 #include "opt_mac.h"
   44 
   45 #include <sys/param.h>
   46 #include <sys/systm.h>
   47 #include <sys/kernel.h>
   48 #include <sys/sysctl.h>
   49 #include <sys/malloc.h>
   50 #include <sys/priv.h>
   51 #include <sys/proc.h>
   52 #include <sys/lock.h>
   53 #include <sys/mutex.h>
   54 #include <sys/sx.h>
   55 #include <sys/sysproto.h>
   56 #include <sys/uio.h>
   57 #ifdef KTRACE
   58 #include <sys/ktrace.h>
   59 #endif
   60 
   61 #include <security/mac/mac_framework.h>
   62 
   63 #include <vm/vm.h>
   64 #include <vm/vm_extern.h>
   65 
   66 static MALLOC_DEFINE(M_SYSCTL, "sysctl", "sysctl internal magic");
   67 static MALLOC_DEFINE(M_SYSCTLOID, "sysctloid", "sysctl dynamic oids");
   68 static MALLOC_DEFINE(M_SYSCTLTMP, "sysctltmp", "sysctl temp output buffer");
   69 
   70 /*
   71  * The sysctllock protects the MIB tree.  It also protects sysctl
   72  * contexts used with dynamic sysctls.  The sysctl_register_oid() and
   73  * sysctl_unregister_oid() routines require the sysctllock to already
   74  * be held, so the sysctl_lock() and sysctl_unlock() routines are
   75  * provided for the few places in the kernel which need to use that
   76  * API rather than using the dynamic API.  Use of the dynamic API is
   77  * strongly encouraged for most code.
   78  *
   79  * The sysctlmemlock is used to limit the amount of user memory wired for
   80  * sysctl requests.  This is implemented by serializing any userland
   81  * sysctl requests larger than a single page via an exclusive lock.
   82  */
   83 static struct sx sysctllock;
   84 static struct sx sysctlmemlock;
   85 
   86 #define SYSCTL_SLOCK()          sx_slock(&sysctllock)
   87 #define SYSCTL_SUNLOCK()        sx_sunlock(&sysctllock)
   88 #define SYSCTL_XLOCK()          sx_xlock(&sysctllock)
   89 #define SYSCTL_XUNLOCK()        sx_xunlock(&sysctllock)
   90 #define SYSCTL_ASSERT_XLOCKED() sx_assert(&sysctllock, SA_XLOCKED)
   91 #define SYSCTL_ASSERT_LOCKED()  sx_assert(&sysctllock, SA_LOCKED)
   92 #define SYSCTL_INIT()           sx_init(&sysctllock, "sysctl lock")
   93 
   94 static int sysctl_root(SYSCTL_HANDLER_ARGS);
   95 
   96 struct sysctl_oid_list sysctl__children; /* root list */
   97 
   98 static int      sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del,
   99                     int recurse);
  100 
  101 static struct sysctl_oid *
  102 sysctl_find_oidname(const char *name, struct sysctl_oid_list *list)
  103 {
  104         struct sysctl_oid *oidp;
  105 
  106         SYSCTL_ASSERT_LOCKED();
  107         SLIST_FOREACH(oidp, list, oid_link) {
  108                 if (strcmp(oidp->oid_name, name) == 0) {
  109                         return (oidp);
  110                 }
  111         }
  112         return (NULL);
  113 }
  114 
  115 /*
  116  * Initialization of the MIB tree.
  117  *
  118  * Order by number in each list.
  119  */
  120 void
  121 sysctl_lock(void)
  122 {
  123 
  124         SYSCTL_XLOCK();
  125 }
  126 
  127 void
  128 sysctl_unlock(void)
  129 {
  130 
  131         SYSCTL_XUNLOCK();
  132 }
  133 
  134 void
  135 sysctl_register_oid(struct sysctl_oid *oidp)
  136 {
  137         struct sysctl_oid_list *parent = oidp->oid_parent;
  138         struct sysctl_oid *p;
  139         struct sysctl_oid *q;
  140 
  141         /*
  142          * First check if another oid with the same name already
  143          * exists in the parent's list.
  144          */
  145         SYSCTL_ASSERT_XLOCKED();
  146         p = sysctl_find_oidname(oidp->oid_name, parent);
  147         if (p != NULL) {
  148                 if ((p->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
  149                         p->oid_refcnt++;
  150                         return;
  151                 } else {
  152                         printf("can't re-use a leaf (%s)!\n", p->oid_name);
  153                         return;
  154                 }
  155         }
  156         /*
  157          * If this oid has a number OID_AUTO, give it a number which
  158          * is greater than any current oid.
  159          * NOTE: DO NOT change the starting value here, change it in
  160          * <sys/sysctl.h>, and make sure it is at least 256 to
  161          * accomodate e.g. net.inet.raw as a static sysctl node.
  162          */
  163         if (oidp->oid_number == OID_AUTO) {
  164                 static int newoid = CTL_AUTO_START;
  165 
  166                 oidp->oid_number = newoid++;
  167                 if (newoid == 0x7fffffff)
  168                         panic("out of oids");
  169         }
  170 #if 0
  171         else if (oidp->oid_number >= CTL_AUTO_START) {
  172                 /* do not panic; this happens when unregistering sysctl sets */
  173                 printf("static sysctl oid too high: %d", oidp->oid_number);
  174         }
  175 #endif
  176 
  177         /*
  178          * Insert the oid into the parent's list in order.
  179          */
  180         q = NULL;
  181         SLIST_FOREACH(p, parent, oid_link) {
  182                 if (oidp->oid_number < p->oid_number)
  183                         break;
  184                 q = p;
  185         }
  186         if (q)
  187                 SLIST_INSERT_AFTER(q, oidp, oid_link);
  188         else
  189                 SLIST_INSERT_HEAD(parent, oidp, oid_link);
  190 }
  191 
  192 void
  193 sysctl_unregister_oid(struct sysctl_oid *oidp)
  194 {
  195         struct sysctl_oid *p;
  196         int error;
  197 
  198         SYSCTL_ASSERT_XLOCKED();
  199         error = ENOENT;
  200         if (oidp->oid_number == OID_AUTO) {
  201                 error = EINVAL;
  202         } else {
  203                 SLIST_FOREACH(p, oidp->oid_parent, oid_link) {
  204                         if (p == oidp) {
  205                                 SLIST_REMOVE(oidp->oid_parent, oidp,
  206                                     sysctl_oid, oid_link);
  207                                 error = 0;
  208                                 break;
  209                         }
  210                 }
  211         }
  212 
  213         /* 
  214          * This can happen when a module fails to register and is
  215          * being unloaded afterwards.  It should not be a panic()
  216          * for normal use.
  217          */
  218         if (error)
  219                 printf("%s: failed to unregister sysctl\n", __func__);
  220 }
  221 
  222 /* Initialize a new context to keep track of dynamically added sysctls. */
  223 int
  224 sysctl_ctx_init(struct sysctl_ctx_list *c)
  225 {
  226 
  227         if (c == NULL) {
  228                 return (EINVAL);
  229         }
  230 
  231         /*
  232          * No locking here, the caller is responsible for not adding
  233          * new nodes to a context until after this function has
  234          * returned.
  235          */
  236         TAILQ_INIT(c);
  237         return (0);
  238 }
  239 
  240 /* Free the context, and destroy all dynamic oids registered in this context */
  241 int
  242 sysctl_ctx_free(struct sysctl_ctx_list *clist)
  243 {
  244         struct sysctl_ctx_entry *e, *e1;
  245         int error;
  246 
  247         error = 0;
  248         /*
  249          * First perform a "dry run" to check if it's ok to remove oids.
  250          * XXX FIXME
  251          * XXX This algorithm is a hack. But I don't know any
  252          * XXX better solution for now...
  253          */
  254         SYSCTL_XLOCK();
  255         TAILQ_FOREACH(e, clist, link) {
  256                 error = sysctl_remove_oid_locked(e->entry, 0, 0);
  257                 if (error)
  258                         break;
  259         }
  260         /*
  261          * Restore deregistered entries, either from the end,
  262          * or from the place where error occured.
  263          * e contains the entry that was not unregistered
  264          */
  265         if (error)
  266                 e1 = TAILQ_PREV(e, sysctl_ctx_list, link);
  267         else
  268                 e1 = TAILQ_LAST(clist, sysctl_ctx_list);
  269         while (e1 != NULL) {
  270                 sysctl_register_oid(e1->entry);
  271                 e1 = TAILQ_PREV(e1, sysctl_ctx_list, link);
  272         }
  273         if (error) {
  274                 SYSCTL_XUNLOCK();
  275                 return(EBUSY);
  276         }
  277         /* Now really delete the entries */
  278         e = TAILQ_FIRST(clist);
  279         while (e != NULL) {
  280                 e1 = TAILQ_NEXT(e, link);
  281                 error = sysctl_remove_oid_locked(e->entry, 1, 0);
  282                 if (error)
  283                         panic("sysctl_remove_oid: corrupt tree, entry: %s",
  284                             e->entry->oid_name);
  285                 free(e, M_SYSCTLOID);
  286                 e = e1;
  287         }
  288         SYSCTL_XUNLOCK();
  289         return (error);
  290 }
  291 
  292 /* Add an entry to the context */
  293 struct sysctl_ctx_entry *
  294 sysctl_ctx_entry_add(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
  295 {
  296         struct sysctl_ctx_entry *e;
  297 
  298         SYSCTL_ASSERT_XLOCKED();
  299         if (clist == NULL || oidp == NULL)
  300                 return(NULL);
  301         e = malloc(sizeof(struct sysctl_ctx_entry), M_SYSCTLOID, M_WAITOK);
  302         e->entry = oidp;
  303         TAILQ_INSERT_HEAD(clist, e, link);
  304         return (e);
  305 }
  306 
  307 /* Find an entry in the context */
  308 struct sysctl_ctx_entry *
  309 sysctl_ctx_entry_find(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
  310 {
  311         struct sysctl_ctx_entry *e;
  312 
  313         SYSCTL_ASSERT_LOCKED();
  314         if (clist == NULL || oidp == NULL)
  315                 return(NULL);
  316         TAILQ_FOREACH(e, clist, link) {
  317                 if(e->entry == oidp)
  318                         return(e);
  319         }
  320         return (e);
  321 }
  322 
  323 /*
  324  * Delete an entry from the context.
  325  * NOTE: this function doesn't free oidp! You have to remove it
  326  * with sysctl_remove_oid().
  327  */
  328 int
  329 sysctl_ctx_entry_del(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
  330 {
  331         struct sysctl_ctx_entry *e;
  332 
  333         if (clist == NULL || oidp == NULL)
  334                 return (EINVAL);
  335         SYSCTL_XLOCK();
  336         e = sysctl_ctx_entry_find(clist, oidp);
  337         if (e != NULL) {
  338                 TAILQ_REMOVE(clist, e, link);
  339                 SYSCTL_XUNLOCK();
  340                 free(e, M_SYSCTLOID);
  341                 return (0);
  342         } else {
  343                 SYSCTL_XUNLOCK();
  344                 return (ENOENT);
  345         }
  346 }
  347 
  348 /*
  349  * Remove dynamically created sysctl trees.
  350  * oidp - top of the tree to be removed
  351  * del - if 0 - just deregister, otherwise free up entries as well
  352  * recurse - if != 0 traverse the subtree to be deleted
  353  */
  354 int
  355 sysctl_remove_oid(struct sysctl_oid *oidp, int del, int recurse)
  356 {
  357         int error;
  358 
  359         SYSCTL_XLOCK();
  360         error = sysctl_remove_oid_locked(oidp, del, recurse);
  361         SYSCTL_XUNLOCK();
  362         return (error);
  363 }
  364 
  365 static int
  366 sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del, int recurse)
  367 {
  368         struct sysctl_oid *p;
  369         int error;
  370 
  371         SYSCTL_ASSERT_XLOCKED();
  372         if (oidp == NULL)
  373                 return(EINVAL);
  374         if ((oidp->oid_kind & CTLFLAG_DYN) == 0) {
  375                 printf("can't remove non-dynamic nodes!\n");
  376                 return (EINVAL);
  377         }
  378         /*
  379          * WARNING: normal method to do this should be through
  380          * sysctl_ctx_free(). Use recursing as the last resort
  381          * method to purge your sysctl tree of leftovers...
  382          * However, if some other code still references these nodes,
  383          * it will panic.
  384          */
  385         if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
  386                 if (oidp->oid_refcnt == 1) {
  387                         SLIST_FOREACH(p, SYSCTL_CHILDREN(oidp), oid_link) {
  388                                 if (!recurse)
  389                                         return (ENOTEMPTY);
  390                                 error = sysctl_remove_oid_locked(p, del,
  391                                     recurse);
  392                                 if (error)
  393                                         return (error);
  394                         }
  395                         if (del)
  396                                 free(SYSCTL_CHILDREN(oidp), M_SYSCTLOID);
  397                 }
  398         }
  399         if (oidp->oid_refcnt > 1 ) {
  400                 oidp->oid_refcnt--;
  401         } else {
  402                 if (oidp->oid_refcnt == 0) {
  403                         printf("Warning: bad oid_refcnt=%u (%s)!\n",
  404                                 oidp->oid_refcnt, oidp->oid_name);
  405                         return (EINVAL);
  406                 }
  407                 sysctl_unregister_oid(oidp);
  408                 if (del) {
  409                         if (oidp->oid_descr)
  410                                 free((void *)(uintptr_t)(const void *)oidp->oid_descr, M_SYSCTLOID);
  411                         free((void *)(uintptr_t)(const void *)oidp->oid_name,
  412                              M_SYSCTLOID);
  413                         free(oidp, M_SYSCTLOID);
  414                 }
  415         }
  416         return (0);
  417 }
  418 
  419 /*
  420  * Create new sysctls at run time.
  421  * clist may point to a valid context initialized with sysctl_ctx_init().
  422  */
  423 struct sysctl_oid *
  424 sysctl_add_oid(struct sysctl_ctx_list *clist, struct sysctl_oid_list *parent,
  425         int number, const char *name, int kind, void *arg1, int arg2,
  426         int (*handler)(SYSCTL_HANDLER_ARGS), const char *fmt, const char *descr)
  427 {
  428         struct sysctl_oid *oidp;
  429         ssize_t len;
  430         char *newname;
  431 
  432         /* You have to hook up somewhere.. */
  433         if (parent == NULL)
  434                 return(NULL);
  435         /* Check if the node already exists, otherwise create it */
  436         SYSCTL_XLOCK();
  437         oidp = sysctl_find_oidname(name, parent);
  438         if (oidp != NULL) {
  439                 if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
  440                         oidp->oid_refcnt++;
  441                         /* Update the context */
  442                         if (clist != NULL)
  443                                 sysctl_ctx_entry_add(clist, oidp);
  444                         SYSCTL_XUNLOCK();
  445                         return (oidp);
  446                 } else {
  447                         SYSCTL_XUNLOCK();
  448                         printf("can't re-use a leaf (%s)!\n", name);
  449                         return (NULL);
  450                 }
  451         }
  452         oidp = malloc(sizeof(struct sysctl_oid), M_SYSCTLOID, M_WAITOK|M_ZERO);
  453         oidp->oid_parent = parent;
  454         SLIST_NEXT(oidp, oid_link) = NULL;
  455         oidp->oid_number = number;
  456         oidp->oid_refcnt = 1;
  457         len = strlen(name);
  458         newname = malloc(len + 1, M_SYSCTLOID, M_WAITOK);
  459         bcopy(name, newname, len + 1);
  460         newname[len] = '\0';
  461         oidp->oid_name = newname;
  462         oidp->oid_handler = handler;
  463         oidp->oid_kind = CTLFLAG_DYN | kind;
  464         if ((kind & CTLTYPE) == CTLTYPE_NODE) {
  465                 /* Allocate space for children */
  466                 SYSCTL_CHILDREN_SET(oidp, malloc(sizeof(struct sysctl_oid_list),
  467                     M_SYSCTLOID, M_WAITOK));
  468                 SLIST_INIT(SYSCTL_CHILDREN(oidp));
  469         } else {
  470                 oidp->oid_arg1 = arg1;
  471                 oidp->oid_arg2 = arg2;
  472         }
  473         oidp->oid_fmt = fmt;
  474         if (descr) {
  475                 int len = strlen(descr) + 1;
  476                 oidp->oid_descr = malloc(len, M_SYSCTLOID, M_WAITOK);
  477                 if (oidp->oid_descr)
  478                         strcpy((char *)(uintptr_t)(const void *)oidp->oid_descr, descr);
  479         }
  480         /* Update the context, if used */
  481         if (clist != NULL)
  482                 sysctl_ctx_entry_add(clist, oidp);
  483         /* Register this oid */
  484         sysctl_register_oid(oidp);
  485         SYSCTL_XUNLOCK();
  486         return (oidp);
  487 }
  488 
  489 /*
  490  * Rename an existing oid.
  491  */
  492 void
  493 sysctl_rename_oid(struct sysctl_oid *oidp, const char *name)
  494 {
  495         ssize_t len;
  496         char *newname;
  497         void *oldname;
  498 
  499         len = strlen(name);
  500         newname = malloc(len + 1, M_SYSCTLOID, M_WAITOK);
  501         bcopy(name, newname, len + 1);
  502         newname[len] = '\0';
  503         SYSCTL_XLOCK();
  504         oldname = (void *)(uintptr_t)(const void *)oidp->oid_name;
  505         oidp->oid_name = newname;
  506         SYSCTL_XUNLOCK();
  507         free(oldname, M_SYSCTLOID);
  508 }
  509 
  510 /*
  511  * Reparent an existing oid.
  512  */
  513 int
  514 sysctl_move_oid(struct sysctl_oid *oid, struct sysctl_oid_list *parent)
  515 {
  516         struct sysctl_oid *oidp;
  517 
  518         SYSCTL_XLOCK();
  519         if (oid->oid_parent == parent) {
  520                 SYSCTL_XUNLOCK();
  521                 return (0);
  522         }
  523         oidp = sysctl_find_oidname(oid->oid_name, parent);
  524         if (oidp != NULL) {
  525                 SYSCTL_XUNLOCK();
  526                 return (EEXIST);
  527         }
  528         sysctl_unregister_oid(oid);
  529         oid->oid_parent = parent;
  530         oid->oid_number = OID_AUTO;
  531         sysctl_register_oid(oid);
  532         SYSCTL_XUNLOCK();
  533         return (0);
  534 }
  535 
  536 /*
  537  * Register the kernel's oids on startup.
  538  */
  539 SET_DECLARE(sysctl_set, struct sysctl_oid);
  540 
  541 static void
  542 sysctl_register_all(void *arg)
  543 {
  544         struct sysctl_oid **oidp;
  545 
  546         sx_init(&sysctlmemlock, "sysctl mem");
  547         SYSCTL_INIT();
  548         SYSCTL_XLOCK();
  549         SET_FOREACH(oidp, sysctl_set)
  550                 sysctl_register_oid(*oidp);
  551         SYSCTL_XUNLOCK();
  552 }
  553 SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_ANY, sysctl_register_all, 0);
  554 
  555 /*
  556  * "Staff-functions"
  557  *
  558  * These functions implement a presently undocumented interface 
  559  * used by the sysctl program to walk the tree, and get the type
  560  * so it can print the value.
  561  * This interface is under work and consideration, and should probably
  562  * be killed with a big axe by the first person who can find the time.
  563  * (be aware though, that the proper interface isn't as obvious as it
  564  * may seem, there are various conflicting requirements.
  565  *
  566  * {0,0}        printf the entire MIB-tree.
  567  * {0,1,...}    return the name of the "..." OID.
  568  * {0,2,...}    return the next OID.
  569  * {0,3}        return the OID of the name in "new"
  570  * {0,4,...}    return the kind & format info for the "..." OID.
  571  * {0,5,...}    return the description the "..." OID.
  572  */
  573 
  574 #ifdef SYSCTL_DEBUG
  575 static void
  576 sysctl_sysctl_debug_dump_node(struct sysctl_oid_list *l, int i)
  577 {
  578         int k;
  579         struct sysctl_oid *oidp;
  580 
  581         SYSCTL_ASSERT_LOCKED();
  582         SLIST_FOREACH(oidp, l, oid_link) {
  583 
  584                 for (k=0; k<i; k++)
  585                         printf(" ");
  586 
  587                 printf("%d %s ", oidp->oid_number, oidp->oid_name);
  588 
  589                 printf("%c%c",
  590                         oidp->oid_kind & CTLFLAG_RD ? 'R':' ',
  591                         oidp->oid_kind & CTLFLAG_WR ? 'W':' ');
  592 
  593                 if (oidp->oid_handler)
  594                         printf(" *Handler");
  595 
  596                 switch (oidp->oid_kind & CTLTYPE) {
  597                         case CTLTYPE_NODE:
  598                                 printf(" Node\n");
  599                                 if (!oidp->oid_handler) {
  600                                         sysctl_sysctl_debug_dump_node(
  601                                                 oidp->oid_arg1, i+2);
  602                                 }
  603                                 break;
  604                         case CTLTYPE_INT:    printf(" Int\n"); break;
  605                         case CTLTYPE_STRING: printf(" String\n"); break;
  606                         case CTLTYPE_QUAD:   printf(" Quad\n"); break;
  607                         case CTLTYPE_OPAQUE: printf(" Opaque/struct\n"); break;
  608                         default:             printf("\n");
  609                 }
  610 
  611         }
  612 }
  613 
  614 static int
  615 sysctl_sysctl_debug(SYSCTL_HANDLER_ARGS)
  616 {
  617         int error;
  618 
  619         error = priv_check(req->td, PRIV_SYSCTL_DEBUG);
  620         if (error)
  621                 return (error);
  622         sysctl_sysctl_debug_dump_node(&sysctl__children, 0);
  623         return (ENOENT);
  624 }
  625 
  626 SYSCTL_PROC(_sysctl, 0, debug, CTLTYPE_STRING|CTLFLAG_RD,
  627         0, 0, sysctl_sysctl_debug, "-", "");
  628 #endif
  629 
  630 static int
  631 sysctl_sysctl_name(SYSCTL_HANDLER_ARGS)
  632 {
  633         int *name = (int *) arg1;
  634         u_int namelen = arg2;
  635         int error = 0;
  636         struct sysctl_oid *oid;
  637         struct sysctl_oid_list *lsp = &sysctl__children, *lsp2;
  638         char buf[10];
  639 
  640         SYSCTL_ASSERT_LOCKED();
  641         while (namelen) {
  642                 if (!lsp) {
  643                         snprintf(buf,sizeof(buf),"%d",*name);
  644                         if (req->oldidx)
  645                                 error = SYSCTL_OUT(req, ".", 1);
  646                         if (!error)
  647                                 error = SYSCTL_OUT(req, buf, strlen(buf));
  648                         if (error)
  649                                 return (error);
  650                         namelen--;
  651                         name++;
  652                         continue;
  653                 }
  654                 lsp2 = 0;
  655                 SLIST_FOREACH(oid, lsp, oid_link) {
  656                         if (oid->oid_number != *name)
  657                                 continue;
  658 
  659                         if (req->oldidx)
  660                                 error = SYSCTL_OUT(req, ".", 1);
  661                         if (!error)
  662                                 error = SYSCTL_OUT(req, oid->oid_name,
  663                                         strlen(oid->oid_name));
  664                         if (error)
  665                                 return (error);
  666 
  667                         namelen--;
  668                         name++;
  669 
  670                         if ((oid->oid_kind & CTLTYPE) != CTLTYPE_NODE) 
  671                                 break;
  672 
  673                         if (oid->oid_handler)
  674                                 break;
  675 
  676                         lsp2 = (struct sysctl_oid_list *)oid->oid_arg1;
  677                         break;
  678                 }
  679                 lsp = lsp2;
  680         }
  681         return (SYSCTL_OUT(req, "", 1));
  682 }
  683 
  684 static SYSCTL_NODE(_sysctl, 1, name, CTLFLAG_RD, sysctl_sysctl_name, "");
  685 
  686 static int
  687 sysctl_sysctl_next_ls(struct sysctl_oid_list *lsp, int *name, u_int namelen, 
  688         int *next, int *len, int level, struct sysctl_oid **oidpp)
  689 {
  690         struct sysctl_oid *oidp;
  691 
  692         SYSCTL_ASSERT_LOCKED();
  693         *len = level;
  694         SLIST_FOREACH(oidp, lsp, oid_link) {
  695                 *next = oidp->oid_number;
  696                 *oidpp = oidp;
  697 
  698                 if (oidp->oid_kind & CTLFLAG_SKIP)
  699                         continue;
  700 
  701                 if (!namelen) {
  702                         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE) 
  703                                 return (0);
  704                         if (oidp->oid_handler) 
  705                                 /* We really should call the handler here...*/
  706                                 return (0);
  707                         lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
  708                         if (!sysctl_sysctl_next_ls(lsp, 0, 0, next+1, 
  709                                 len, level+1, oidpp))
  710                                 return (0);
  711                         goto emptynode;
  712                 }
  713 
  714                 if (oidp->oid_number < *name)
  715                         continue;
  716 
  717                 if (oidp->oid_number > *name) {
  718                         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
  719                                 return (0);
  720                         if (oidp->oid_handler)
  721                                 return (0);
  722                         lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
  723                         if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1, 
  724                                 next+1, len, level+1, oidpp))
  725                                 return (0);
  726                         goto next;
  727                 }
  728                 if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
  729                         continue;
  730 
  731                 if (oidp->oid_handler)
  732                         continue;
  733 
  734                 lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
  735                 if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1, next+1, 
  736                         len, level+1, oidpp))
  737                         return (0);
  738         next:
  739                 namelen = 1;
  740         emptynode:
  741                 *len = level;
  742         }
  743         return (1);
  744 }
  745 
  746 static int
  747 sysctl_sysctl_next(SYSCTL_HANDLER_ARGS)
  748 {
  749         int *name = (int *) arg1;
  750         u_int namelen = arg2;
  751         int i, j, error;
  752         struct sysctl_oid *oid;
  753         struct sysctl_oid_list *lsp = &sysctl__children;
  754         int newoid[CTL_MAXNAME];
  755 
  756         i = sysctl_sysctl_next_ls(lsp, name, namelen, newoid, &j, 1, &oid);
  757         if (i)
  758                 return (ENOENT);
  759         error = SYSCTL_OUT(req, newoid, j * sizeof (int));
  760         return (error);
  761 }
  762 
  763 static SYSCTL_NODE(_sysctl, 2, next, CTLFLAG_RD, sysctl_sysctl_next, "");
  764 
  765 static int
  766 name2oid(char *name, int *oid, int *len, struct sysctl_oid **oidpp)
  767 {
  768         int i;
  769         struct sysctl_oid *oidp;
  770         struct sysctl_oid_list *lsp = &sysctl__children;
  771         char *p;
  772 
  773         SYSCTL_ASSERT_LOCKED();
  774 
  775         if (!*name)
  776                 return (ENOENT);
  777 
  778         p = name + strlen(name) - 1 ;
  779         if (*p == '.')
  780                 *p = '\0';
  781 
  782         *len = 0;
  783 
  784         for (p = name; *p && *p != '.'; p++) 
  785                 ;
  786         i = *p;
  787         if (i == '.')
  788                 *p = '\0';
  789 
  790         oidp = SLIST_FIRST(lsp);
  791 
  792         while (oidp && *len < CTL_MAXNAME) {
  793                 if (strcmp(name, oidp->oid_name)) {
  794                         oidp = SLIST_NEXT(oidp, oid_link);
  795                         continue;
  796                 }
  797                 *oid++ = oidp->oid_number;
  798                 (*len)++;
  799 
  800                 if (!i) {
  801                         if (oidpp)
  802                                 *oidpp = oidp;
  803                         return (0);
  804                 }
  805 
  806                 if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
  807                         break;
  808 
  809                 if (oidp->oid_handler)
  810                         break;
  811 
  812                 lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
  813                 oidp = SLIST_FIRST(lsp);
  814                 name = p+1;
  815                 for (p = name; *p && *p != '.'; p++) 
  816                                 ;
  817                 i = *p;
  818                 if (i == '.')
  819                         *p = '\0';
  820         }
  821         return (ENOENT);
  822 }
  823 
  824 static int
  825 sysctl_sysctl_name2oid(SYSCTL_HANDLER_ARGS)
  826 {
  827         char *p;
  828         int error, oid[CTL_MAXNAME], len;
  829         struct sysctl_oid *op = 0;
  830 
  831         SYSCTL_ASSERT_LOCKED();
  832 
  833         if (!req->newlen) 
  834                 return (ENOENT);
  835         if (req->newlen >= MAXPATHLEN)  /* XXX arbitrary, undocumented */
  836                 return (ENAMETOOLONG);
  837 
  838         p = malloc(req->newlen+1, M_SYSCTL, M_WAITOK);
  839 
  840         error = SYSCTL_IN(req, p, req->newlen);
  841         if (error) {
  842                 free(p, M_SYSCTL);
  843                 return (error);
  844         }
  845 
  846         p [req->newlen] = '\0';
  847 
  848         error = name2oid(p, oid, &len, &op);
  849 
  850         free(p, M_SYSCTL);
  851 
  852         if (error)
  853                 return (error);
  854 
  855         error = SYSCTL_OUT(req, oid, len * sizeof *oid);
  856         return (error);
  857 }
  858 
  859 SYSCTL_PROC(_sysctl, 3, name2oid, CTLFLAG_RW|CTLFLAG_ANYBODY|CTLFLAG_MPSAFE,
  860     0, 0, sysctl_sysctl_name2oid, "I", "");
  861 
  862 static int
  863 sysctl_sysctl_oidfmt(SYSCTL_HANDLER_ARGS)
  864 {
  865         struct sysctl_oid *oid;
  866         int error;
  867 
  868         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
  869         if (error)
  870                 return (error);
  871 
  872         if (!oid->oid_fmt)
  873                 return (ENOENT);
  874         error = SYSCTL_OUT(req, &oid->oid_kind, sizeof(oid->oid_kind));
  875         if (error)
  876                 return (error);
  877         error = SYSCTL_OUT(req, oid->oid_fmt, strlen(oid->oid_fmt) + 1);
  878         return (error);
  879 }
  880 
  881 
  882 static SYSCTL_NODE(_sysctl, 4, oidfmt, CTLFLAG_RD|CTLFLAG_MPSAFE,
  883     sysctl_sysctl_oidfmt, "");
  884 
  885 static int
  886 sysctl_sysctl_oiddescr(SYSCTL_HANDLER_ARGS)
  887 {
  888         struct sysctl_oid *oid;
  889         int error;
  890 
  891         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
  892         if (error)
  893                 return (error);
  894 
  895         if (!oid->oid_descr)
  896                 return (ENOENT);
  897         error = SYSCTL_OUT(req, oid->oid_descr, strlen(oid->oid_descr) + 1);
  898         return (error);
  899 }
  900 
  901 static SYSCTL_NODE(_sysctl, 5, oiddescr, CTLFLAG_RD, sysctl_sysctl_oiddescr, "");
  902 
  903 /*
  904  * Default "handler" functions.
  905  */
  906 
  907 /*
  908  * Handle an int, signed or unsigned.
  909  * Two cases:
  910  *     a variable:  point arg1 at it.
  911  *     a constant:  pass it in arg2.
  912  */
  913 
  914 int
  915 sysctl_handle_int(SYSCTL_HANDLER_ARGS)
  916 {
  917         int tmpout, error = 0;
  918 
  919         /*
  920          * Attempt to get a coherent snapshot by making a copy of the data.
  921          */
  922         if (arg1)
  923                 tmpout = *(int *)arg1;
  924         else
  925                 tmpout = arg2;
  926         error = SYSCTL_OUT(req, &tmpout, sizeof(int));
  927 
  928         if (error || !req->newptr)
  929                 return (error);
  930 
  931         if (!arg1)
  932                 error = EPERM;
  933         else
  934                 error = SYSCTL_IN(req, arg1, sizeof(int));
  935         return (error);
  936 }
  937 
  938 
  939 /*
  940  * Based on on sysctl_handle_int() convert milliseconds into ticks.
  941  */
  942 
  943 int
  944 sysctl_msec_to_ticks(SYSCTL_HANDLER_ARGS)
  945 {
  946         int error, s, tt;
  947 
  948         tt = *(int *)oidp->oid_arg1;
  949         s = (int)((int64_t)tt * 1000 / hz);
  950 
  951         error = sysctl_handle_int(oidp, &s, 0, req);
  952         if (error || !req->newptr)
  953                 return (error);
  954 
  955         tt = (int)((int64_t)s * hz / 1000);
  956         if (tt < 1)
  957                 return (EINVAL);
  958 
  959         *(int *)oidp->oid_arg1 = tt;
  960         return (0);
  961 }
  962 
  963 
  964 /*
  965  * Handle a long, signed or unsigned.  arg1 points to it.
  966  */
  967 
  968 int
  969 sysctl_handle_long(SYSCTL_HANDLER_ARGS)
  970 {
  971         int error = 0;
  972         long tmplong;
  973 #ifdef SCTL_MASK32
  974         int tmpint;
  975 #endif
  976 
  977         /*
  978          * Attempt to get a coherent snapshot by making a copy of the data.
  979          */
  980         if (!arg1)
  981                 return (EINVAL);
  982         tmplong = *(long *)arg1;
  983 #ifdef SCTL_MASK32
  984         if (req->flags & SCTL_MASK32) {
  985                 tmpint = tmplong;
  986                 error = SYSCTL_OUT(req, &tmpint, sizeof(int));
  987         } else
  988 #endif
  989                 error = SYSCTL_OUT(req, &tmplong, sizeof(long));
  990 
  991         if (error || !req->newptr)
  992                 return (error);
  993 
  994 #ifdef SCTL_MASK32
  995         if (req->flags & SCTL_MASK32) {
  996                 error = SYSCTL_IN(req, &tmpint, sizeof(int));
  997                 *(long *)arg1 = (long)tmpint;
  998         } else
  999 #endif
 1000                 error = SYSCTL_IN(req, arg1, sizeof(long));
 1001         return (error);
 1002 }
 1003 
 1004 /*
 1005  * Handle a 64 bit int, signed or unsigned.  arg1 points to it.
 1006  */
 1007 
 1008 int
 1009 sysctl_handle_quad(SYSCTL_HANDLER_ARGS)
 1010 {
 1011         int error = 0;
 1012         uint64_t tmpout;
 1013 
 1014         /*
 1015          * Attempt to get a coherent snapshot by making a copy of the data.
 1016          */
 1017         if (!arg1)
 1018                 return (EINVAL);
 1019         tmpout = *(uint64_t *)arg1;
 1020         error = SYSCTL_OUT(req, &tmpout, sizeof(uint64_t));
 1021 
 1022         if (error || !req->newptr)
 1023                 return (error);
 1024 
 1025         error = SYSCTL_IN(req, arg1, sizeof(uint64_t));
 1026         return (error);
 1027 }
 1028 
 1029 /*
 1030  * Handle our generic '\0' terminated 'C' string.
 1031  * Two cases:
 1032  *      a variable string:  point arg1 at it, arg2 is max length.
 1033  *      a constant string:  point arg1 at it, arg2 is zero.
 1034  */
 1035 
 1036 int
 1037 sysctl_handle_string(SYSCTL_HANDLER_ARGS)
 1038 {
 1039         int error=0;
 1040         char *tmparg;
 1041         size_t outlen;
 1042 
 1043         /*
 1044          * Attempt to get a coherent snapshot by copying to a
 1045          * temporary kernel buffer.
 1046          */
 1047 retry:
 1048         outlen = strlen((char *)arg1)+1;
 1049         tmparg = malloc(outlen, M_SYSCTLTMP, M_WAITOK);
 1050 
 1051         if (strlcpy(tmparg, (char *)arg1, outlen) >= outlen) {
 1052                 free(tmparg, M_SYSCTLTMP);
 1053                 goto retry;
 1054         }
 1055 
 1056         error = SYSCTL_OUT(req, tmparg, outlen);
 1057         free(tmparg, M_SYSCTLTMP);
 1058 
 1059         if (error || !req->newptr)
 1060                 return (error);
 1061 
 1062         if ((req->newlen - req->newidx) >= arg2) {
 1063                 error = EINVAL;
 1064         } else {
 1065                 arg2 = (req->newlen - req->newidx);
 1066                 error = SYSCTL_IN(req, arg1, arg2);
 1067                 ((char *)arg1)[arg2] = '\0';
 1068         }
 1069 
 1070         return (error);
 1071 }
 1072 
 1073 /*
 1074  * Handle any kind of opaque data.
 1075  * arg1 points to it, arg2 is the size.
 1076  */
 1077 
 1078 int
 1079 sysctl_handle_opaque(SYSCTL_HANDLER_ARGS)
 1080 {
 1081         int error, tries;
 1082         u_int generation;
 1083         struct sysctl_req req2;
 1084 
 1085         /*
 1086          * Attempt to get a coherent snapshot, by using the thread
 1087          * pre-emption counter updated from within mi_switch() to
 1088          * determine if we were pre-empted during a bcopy() or
 1089          * copyout(). Make 3 attempts at doing this before giving up.
 1090          * If we encounter an error, stop immediately.
 1091          */
 1092         tries = 0;
 1093         req2 = *req;
 1094 retry:
 1095         generation = curthread->td_generation;
 1096         error = SYSCTL_OUT(req, arg1, arg2);
 1097         if (error)
 1098                 return (error);
 1099         tries++;
 1100         if (generation != curthread->td_generation && tries < 3) {
 1101                 *req = req2;
 1102                 goto retry;
 1103         }
 1104 
 1105         error = SYSCTL_IN(req, arg1, arg2);
 1106 
 1107         return (error);
 1108 }
 1109 
 1110 /*
 1111  * Transfer functions to/from kernel space.
 1112  * XXX: rather untested at this point
 1113  */
 1114 static int
 1115 sysctl_old_kernel(struct sysctl_req *req, const void *p, size_t l)
 1116 {
 1117         size_t i = 0;
 1118 
 1119         if (req->oldptr) {
 1120                 i = l;
 1121                 if (req->oldlen <= req->oldidx)
 1122                         i = 0;
 1123                 else
 1124                         if (i > req->oldlen - req->oldidx)
 1125                                 i = req->oldlen - req->oldidx;
 1126                 if (i > 0)
 1127                         bcopy(p, (char *)req->oldptr + req->oldidx, i);
 1128         }
 1129         req->oldidx += l;
 1130         if (req->oldptr && i != l)
 1131                 return (ENOMEM);
 1132         return (0);
 1133 }
 1134 
 1135 static int
 1136 sysctl_new_kernel(struct sysctl_req *req, void *p, size_t l)
 1137 {
 1138         if (!req->newptr)
 1139                 return (0);
 1140         if (req->newlen - req->newidx < l)
 1141                 return (EINVAL);
 1142         bcopy((char *)req->newptr + req->newidx, p, l);
 1143         req->newidx += l;
 1144         return (0);
 1145 }
 1146 
 1147 int
 1148 kernel_sysctl(struct thread *td, int *name, u_int namelen, void *old,
 1149     size_t *oldlenp, void *new, size_t newlen, size_t *retval, int flags)
 1150 {
 1151         int error = 0;
 1152         struct sysctl_req req;
 1153 
 1154         bzero(&req, sizeof req);
 1155 
 1156         req.td = td;
 1157         req.flags = flags;
 1158 
 1159         if (oldlenp) {
 1160                 req.oldlen = *oldlenp;
 1161         }
 1162         req.validlen = req.oldlen;
 1163 
 1164         if (old) {
 1165                 req.oldptr= old;
 1166         }
 1167 
 1168         if (new != NULL) {
 1169                 req.newlen = newlen;
 1170                 req.newptr = new;
 1171         }
 1172 
 1173         req.oldfunc = sysctl_old_kernel;
 1174         req.newfunc = sysctl_new_kernel;
 1175         req.lock = REQ_LOCKED;
 1176 
 1177         SYSCTL_SLOCK();
 1178         error = sysctl_root(0, name, namelen, &req);
 1179         SYSCTL_SUNLOCK();
 1180 
 1181         if (req.lock == REQ_WIRED && req.validlen > 0)
 1182                 vsunlock(req.oldptr, req.validlen);
 1183 
 1184         if (error && error != ENOMEM)
 1185                 return (error);
 1186 
 1187         if (retval) {
 1188                 if (req.oldptr && req.oldidx > req.validlen)
 1189                         *retval = req.validlen;
 1190                 else
 1191                         *retval = req.oldidx;
 1192         }
 1193         return (error);
 1194 }
 1195 
 1196 int
 1197 kernel_sysctlbyname(struct thread *td, char *name, void *old, size_t *oldlenp,
 1198     void *new, size_t newlen, size_t *retval, int flags)
 1199 {
 1200         int oid[CTL_MAXNAME];
 1201         size_t oidlen, plen;
 1202         int error;
 1203 
 1204         oid[0] = 0;             /* sysctl internal magic */
 1205         oid[1] = 3;             /* name2oid */
 1206         oidlen = sizeof(oid);
 1207 
 1208         error = kernel_sysctl(td, oid, 2, oid, &oidlen,
 1209             (void *)name, strlen(name), &plen, flags);
 1210         if (error)
 1211                 return (error);
 1212 
 1213         error = kernel_sysctl(td, oid, plen / sizeof(int), old, oldlenp,
 1214             new, newlen, retval, flags);
 1215         return (error);
 1216 }
 1217 
 1218 /*
 1219  * Transfer function to/from user space.
 1220  */
 1221 static int
 1222 sysctl_old_user(struct sysctl_req *req, const void *p, size_t l)
 1223 {
 1224         int error = 0;
 1225         size_t i, len, origidx;
 1226 
 1227         origidx = req->oldidx;
 1228         req->oldidx += l;
 1229         if (req->oldptr == NULL)
 1230                 return (0);
 1231         /*
 1232          * If we have not wired the user supplied buffer and we are currently
 1233          * holding locks, drop a witness warning, as it's possible that
 1234          * write operations to the user page can sleep.
 1235          */
 1236         if (req->lock != REQ_WIRED)
 1237                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
 1238                     "sysctl_old_user()");
 1239         i = l;
 1240         len = req->validlen;
 1241         if (len <= origidx)
 1242                 i = 0;
 1243         else {
 1244                 if (i > len - origidx)
 1245                         i = len - origidx;
 1246                 error = copyout(p, (char *)req->oldptr + origidx, i);
 1247         }
 1248         if (error)
 1249                 return (error);
 1250         if (i < l)
 1251                 return (ENOMEM);
 1252         return (0);
 1253 }
 1254 
 1255 static int
 1256 sysctl_new_user(struct sysctl_req *req, void *p, size_t l)
 1257 {
 1258         int error;
 1259 
 1260         if (!req->newptr)
 1261                 return (0);
 1262         if (req->newlen - req->newidx < l)
 1263                 return (EINVAL);
 1264         WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
 1265             "sysctl_new_user()");
 1266         error = copyin((char *)req->newptr + req->newidx, p, l);
 1267         req->newidx += l;
 1268         return (error);
 1269 }
 1270 
 1271 /*
 1272  * Wire the user space destination buffer.  If set to a value greater than
 1273  * zero, the len parameter limits the maximum amount of wired memory.
 1274  */
 1275 int
 1276 sysctl_wire_old_buffer(struct sysctl_req *req, size_t len)
 1277 {
 1278         int ret;
 1279         size_t i, wiredlen;
 1280         char *cp, dummy;
 1281 
 1282         wiredlen = (len > 0 && len < req->oldlen) ? len : req->oldlen;
 1283         ret = 0;
 1284         if (req->lock == REQ_LOCKED && req->oldptr &&
 1285             req->oldfunc == sysctl_old_user) {
 1286                 if (wiredlen != 0) {
 1287                         ret = vslock(req->oldptr, wiredlen);
 1288                         if (ret != 0) {
 1289                                 if (ret != ENOMEM)
 1290                                         return (ret);
 1291                                 wiredlen = 0;
 1292                         }
 1293                         /*
 1294                          * Touch all the wired pages to avoid PTE modified
 1295                          * bit emulation traps on Alpha while holding locks
 1296                          * in the sysctl handler.
 1297                          */
 1298                         for (i = (wiredlen + PAGE_SIZE - 1) / PAGE_SIZE,
 1299                             cp = req->oldptr; i > 0; i--, cp += PAGE_SIZE) {
 1300                                 copyin(cp, &dummy, 1);
 1301                                 copyout(&dummy, cp, 1);
 1302                         }
 1303                 }
 1304                 req->lock = REQ_WIRED;
 1305                 req->validlen = wiredlen;
 1306         }
 1307         return (0);
 1308 }
 1309 
 1310 int
 1311 sysctl_find_oid(int *name, u_int namelen, struct sysctl_oid **noid,
 1312     int *nindx, struct sysctl_req *req)
 1313 {
 1314         struct sysctl_oid *oid;
 1315         int indx;
 1316 
 1317         SYSCTL_ASSERT_LOCKED();
 1318         oid = SLIST_FIRST(&sysctl__children);
 1319         indx = 0;
 1320         while (oid && indx < CTL_MAXNAME) {
 1321                 if (oid->oid_number == name[indx]) {
 1322                         indx++;
 1323                         if (oid->oid_kind & CTLFLAG_NOLOCK)
 1324                                 req->lock = REQ_UNLOCKED;
 1325                         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 1326                                 if (oid->oid_handler != NULL ||
 1327                                     indx == namelen) {
 1328                                         *noid = oid;
 1329                                         if (nindx != NULL)
 1330                                                 *nindx = indx;
 1331                                         return (0);
 1332                                 }
 1333                                 oid = SLIST_FIRST(
 1334                                     (struct sysctl_oid_list *)oid->oid_arg1);
 1335                         } else if (indx == namelen) {
 1336                                 *noid = oid;
 1337                                 if (nindx != NULL)
 1338                                         *nindx = indx;
 1339                                 return (0);
 1340                         } else {
 1341                                 return (ENOTDIR);
 1342                         }
 1343                 } else {
 1344                         oid = SLIST_NEXT(oid, oid_link);
 1345                 }
 1346         }
 1347         return (ENOENT);
 1348 }
 1349 
 1350 /*
 1351  * Traverse our tree, and find the right node, execute whatever it points
 1352  * to, and return the resulting error code.
 1353  */
 1354 
 1355 static int
 1356 sysctl_root(SYSCTL_HANDLER_ARGS)
 1357 {
 1358         struct sysctl_oid *oid;
 1359         int error, indx, lvl;
 1360 
 1361         SYSCTL_ASSERT_LOCKED();
 1362 
 1363         error = sysctl_find_oid(arg1, arg2, &oid, &indx, req);
 1364         if (error)
 1365                 return (error);
 1366 
 1367         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 1368                 /*
 1369                  * You can't call a sysctl when it's a node, but has
 1370                  * no handler.  Inform the user that it's a node.
 1371                  * The indx may or may not be the same as namelen.
 1372                  */
 1373                 if (oid->oid_handler == NULL)
 1374                         return (EISDIR);
 1375         }
 1376 
 1377         /* Is this sysctl writable? */
 1378         if (req->newptr && !(oid->oid_kind & CTLFLAG_WR))
 1379                 return (EPERM);
 1380 
 1381         KASSERT(req->td != NULL, ("sysctl_root(): req->td == NULL"));
 1382 
 1383         /* Is this sysctl sensitive to securelevels? */
 1384         if (req->newptr && (oid->oid_kind & CTLFLAG_SECURE)) {
 1385                 lvl = (oid->oid_kind & CTLMASK_SECURE) >> CTLSHIFT_SECURE;
 1386                 error = securelevel_gt(req->td->td_ucred, lvl);
 1387                 if (error)
 1388                         return (error);
 1389         }
 1390 
 1391         /* Is this sysctl writable by only privileged users? */
 1392         if (req->newptr && !(oid->oid_kind & CTLFLAG_ANYBODY)) {
 1393                 if (oid->oid_kind & CTLFLAG_PRISON)
 1394                         error = priv_check(req->td, PRIV_SYSCTL_WRITEJAIL);
 1395                 else
 1396                         error = priv_check(req->td, PRIV_SYSCTL_WRITE);
 1397                 if (error)
 1398                         return (error);
 1399         }
 1400 
 1401         if (!oid->oid_handler)
 1402                 return (EINVAL);
 1403 
 1404         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 1405                 arg1 = (int *)arg1 + indx;
 1406                 arg2 -= indx;
 1407         } else {
 1408                 arg1 = oid->oid_arg1;
 1409                 arg2 = oid->oid_arg2;
 1410         }
 1411 #ifdef MAC
 1412         error = mac_check_system_sysctl(req->td->td_ucred, oid, arg1, arg2,
 1413             req);
 1414         if (error != 0)
 1415                 return (error);
 1416 #endif
 1417         if (!(oid->oid_kind & CTLFLAG_MPSAFE))
 1418                 mtx_lock(&Giant);
 1419         error = oid->oid_handler(oid, arg1, arg2, req);
 1420         if (!(oid->oid_kind & CTLFLAG_MPSAFE))
 1421                 mtx_unlock(&Giant);
 1422 
 1423         return (error);
 1424 }
 1425 
 1426 #ifndef _SYS_SYSPROTO_H_
 1427 struct sysctl_args {
 1428         int     *name;
 1429         u_int   namelen;
 1430         void    *old;
 1431         size_t  *oldlenp;
 1432         void    *new;
 1433         size_t  newlen;
 1434 };
 1435 #endif
 1436 int
 1437 __sysctl(struct thread *td, struct sysctl_args *uap)
 1438 {
 1439         int error, i, name[CTL_MAXNAME];
 1440         size_t j;
 1441 
 1442         if (uap->namelen > CTL_MAXNAME || uap->namelen < 2)
 1443                 return (EINVAL);
 1444 
 1445         error = copyin(uap->name, &name, uap->namelen * sizeof(int));
 1446         if (error)
 1447                 return (error);
 1448 
 1449         error = userland_sysctl(td, name, uap->namelen,
 1450                 uap->old, uap->oldlenp, 0,
 1451                 uap->new, uap->newlen, &j, 0);
 1452         if (error && error != ENOMEM)
 1453                 return (error);
 1454         if (uap->oldlenp) {
 1455                 i = copyout(&j, uap->oldlenp, sizeof(j));
 1456                 if (i)
 1457                         return (i);
 1458         }
 1459         return (error);
 1460 }
 1461 
 1462 /*
 1463  * This is used from various compatibility syscalls too.  That's why name
 1464  * must be in kernel space.
 1465  */
 1466 int
 1467 userland_sysctl(struct thread *td, int *name, u_int namelen, void *old,
 1468     size_t *oldlenp, int inkernel, void *new, size_t newlen, size_t *retval,
 1469     int flags)
 1470 {
 1471         int error = 0, memlocked;
 1472         struct sysctl_req req;
 1473 
 1474         bzero(&req, sizeof req);
 1475 
 1476         req.td = td;
 1477         req.flags = flags;
 1478 
 1479         if (oldlenp) {
 1480                 if (inkernel) {
 1481                         req.oldlen = *oldlenp;
 1482                 } else {
 1483                         error = copyin(oldlenp, &req.oldlen, sizeof(*oldlenp));
 1484                         if (error)
 1485                                 return (error);
 1486                 }
 1487         }
 1488         req.validlen = req.oldlen;
 1489 
 1490         if (old) {
 1491                 if (!useracc(old, req.oldlen, VM_PROT_WRITE))
 1492                         return (EFAULT);
 1493                 req.oldptr= old;
 1494         }
 1495 
 1496         if (new != NULL) {
 1497                 if (!useracc(new, newlen, VM_PROT_READ))
 1498                         return (EFAULT);
 1499                 req.newlen = newlen;
 1500                 req.newptr = new;
 1501         }
 1502 
 1503         req.oldfunc = sysctl_old_user;
 1504         req.newfunc = sysctl_new_user;
 1505         req.lock = REQ_LOCKED;
 1506 
 1507 #ifdef KTRACE
 1508         if (KTRPOINT(curthread, KTR_SYSCTL))
 1509                 ktrsysctl(name, namelen);
 1510 #endif
 1511 
 1512         if (req.oldlen > PAGE_SIZE) {
 1513                 memlocked = 1;
 1514                 sx_xlock(&sysctlmemlock);
 1515         } else
 1516                 memlocked = 0;
 1517 
 1518         for (;;) {
 1519                 req.oldidx = 0;
 1520                 req.newidx = 0;
 1521                 SYSCTL_SLOCK();
 1522                 error = sysctl_root(0, name, namelen, &req);
 1523                 SYSCTL_SUNLOCK();
 1524                 if (error != EAGAIN)
 1525                         break;
 1526                 uio_yield();
 1527         }
 1528 
 1529 
 1530         if (req.lock == REQ_WIRED && req.validlen > 0)
 1531                 vsunlock(req.oldptr, req.validlen);
 1532         if (memlocked)
 1533                 sx_xunlock(&sysctlmemlock);
 1534 
 1535         if (error && error != ENOMEM)
 1536                 return (error);
 1537 
 1538         if (retval) {
 1539                 if (req.oldptr && req.oldidx > req.validlen)
 1540                         *retval = req.validlen;
 1541                 else
 1542                         *retval = req.oldidx;
 1543         }
 1544         return (error);
 1545 }

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